Detectable PSA After Prostatectomy

One of the advantages of choosing surgery over radiation to treat localized prostate cancer is that the PSA becomes a perfect marker to know if one is cured or not. The outcome we are looking for is an undetectable PSA such that the lab result has a less than sign in front of a number that indicates the sensitivity of the machine that ran the test. This is usually achieved, certainly at first after a prostatectomy. However, it is not at all uncommon to see the PSA become detectable, even after the first three-month result is undetectable.

When this happens, we must first understand the implication of this finding. If the prostate has been removed (understand that PSA stands for a prostate-specific antigen, meaning it is only made by prostate cells), a detectable PSA means that prostate cells are present somewhere in the body. There are three possibilities.

• First, this could mean that the prostate cancer spread or metastasized and now is in a distant site such as in a bone or lymph nodes. Typically, in this case, the PSA never becomes undetectable after surgery, or the undetectable result is very short-lived. Here, as usually only aggressive cells spread, the PSA rises relatively rapidly, called a short doubling time. This is because if this is the case, those cells that spread did so before surgery and thus would continue to grow even right after surgery and never stop.
• The second and most common option is that the detectable PSA suggests local recurrence or that some cells that invaded into tissues next to the prostate, such as the rectum or bladder, were left behind. A typical pattern for this is a recurrence, perhaps at one year, with slow and steady increases seen in the PSA over time and a slower doubling time than that seen with metastatic disease.
• The final possibility and this tends to be more present earlier in one’s robotic prostatectomy series as one improves technically, is that the detectable PSA is from a small island of benign prostatic tissue left behind at surgery, perhaps embedded in the bladder wall and not recognized. Since this would be very slow growing, this can be responsible for a barely detectable PSA seen many years after surgery, with a very slow growth pattern.

Thus, one can see that when the PSA becomes detectable, the first thing to do is to follow it and let it present itself as one of these three patterns. This is important as each scenario is treated differently, so classification to the best of our ability is important. If the most likely cause is metastasis, secondary or salvage radiation to the pelvis is not usually successful as the cancer is likely present outside the field that is to be radiated. Here, we will obtain a radiologic study called a PSMA (prostate-specific membrane antigen) study that will look for specific sites of metastasis as targets for radiation. In this case, if a target is found, we call this focal radiation, and generally, it is thought of as a temporizing measure and not a cure, as usually, if a target is seen, there are others that are not seen. The mainstay of treatment for metastatic prostate cancer is hormone therapy, often given intermittently, and not radiation therapy. Typically, hormone therapy is not initiated until the PSA reaches fifteen or twenty, so even when patients have a detectable PSA and may be metastatic, often they are only followed and not treated for several years. Hormone therapy will typically have efficacy for many years beyond that point.

The more common scenario is the PSA recurrence pattern that suggests local recurrence only. Here again, a PSMA scan is obtained. However, the sensitivity of this scan when the PSA is very low is poor, so it has limited utility here in finding specific targets. In this case, we try to decide to proceed with radiation early as the goal here with salvage radiation is to cure the patient, not just slow down the cancer. The literature varies on the ideal point to offer radiation, but the general consensus is that it should be performed when the PSA is between .3 and .5. This usually still gives some time to follow the PSA to make sure it is rising, but it does force the patient to make a conscious decision as to whether they want to have radiation and seek a cure or not early on. Waiting longer lowers the cure rate. This can be a hard decision for some, as it is not always clear that seeking a cure will affect one’s life expectancy. For some, simply watching PSA slowly rise and accepting possible asymptomatic metastasis makes more sense than risking potential side effects such as scarring or incontinence from radiation. We call this act of following only watchful waiting with delayed institution of intermittent hormone therapy. Sometimes, this is the right choice based on a patient’s age, life expectancy, and risk stratification of the prostate cancer.

In the third scenario, where many years have passed, and the PSA is low and barely rising, it becomes far more logical not to offer radiation as it will have no benefit for benign tissue. Even if the PSA is from some local recurrence, if the PSA is rising extremely slowly, the number of years it would take to reach fifteen or twenty far surpasses one’s life expectancy. The point here being that just because a PSA becomes detectable does not mean radiation or other treatment makes sense, and that many will never need the recurrent PSA addressed at all.

Having a detectable PSA after prostatectomy is usually not a cause for panic. It is time to take a deep breath, learn about the problem, and make a wise decision regarding the next steps that consider life expectancy, the potential impact of the recurrence, or the proposed radiation treatment that would happen, and then make a team-based shared decision as to what to do. A detectable PSA does not mean that undergoing surgery was a mistake, and the surgery will still provide long-term benefits.